percent_bar_delegate.h

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#ifndef PERCENTBARDELEGATE_H
#define PERCENTBARDELEGATE_H
 
/*
 * @file Percent bar delegate.
 *
 * QStyledItemDelegate subclass that will draw a percentage value and a
 * single-item bar chart for the specified value.
 *
 * This is intended to be used in QTreeWidgets to show percentage values.
 * To use it, first call setItemDelegate:
 *
 *   myTreeWidget()->setItemDelegateForColumn(col_pct_, new PercentBarDelegate());
 *
 * Then, for each QTreeWidgetItem, set a double value using setData:
 *
 *   setData(col_pct_, Qt::UserRole, QVariant::fromValue<double>(packets_ * 100.0 / num_packets));
 *
 * If the item data cannot be converted to a valid double value or if its
 * text string is non-empty then it will be rendered normally (i.e. the
 * percent text and bar will not be drawn). This lets you mix normal and
 * percent bar rendering between rows.
 */
 
#include <QStyledItemDelegate>

class PercentBarDelegate : public QStyledItemDelegate
{
public:
    PercentBarDelegate(QWidget *parent = 0) : QStyledItemDelegate(parent) { }

    virtual QString displayText(const QVariant &, const QLocale &) const override { return QString(); }
 
protected:
    void paint(QPainter *painter, const QStyleOptionViewItem &option,
               const QModelIndex &index) const override;

    QSize sizeHint(const QStyleOptionViewItem &option,
                   const QModelIndex &index) const override;
 
};
 
#endif // PERCENTBARDELEGATE_H